XSL Transformation (XSLT) XSLT Processors. Example XSLT Stylesheet. Calling XSLT Processor. XSLT Structure

Transcription

1 Transformation (T) SOURCE <CATALOG> <TITLE>The very best of</title> <ARTIST>Cat Stevens</ARTIST> <COUNTRY>UK</COUNTRY> <PRICE>8.90</PRICE> <YEAR>1990</YEAR> <TITLE>Empire Burlesque</TITLE> <ARTIST>Bob Dylan</ARTIST> <COUNTRY>USA</COUNTRY> <PRICE>10.90</PRICE> <YEAR>1985</YEAR> </CATALOG> <table border="2"> <th>title</th> <th>artist</th> <td>empire Burlesque</td> <td>bob Dylan</td> <td>the very best of</td> <td>cat Stevens</td> </table> T Stylesheet <xsl:stylesheet /> <xsl:template match="/catalog"> <table border="2"> <th>title</th> <th>artist</th> <xsl:apply-templates select="cd" /> </table> <xsl:template match="cd"> <td><xsl:value-of select="title"/></td> <td><xsl:value-of select="artist"/></td> T Processors SAXON saxon.sourceforge.net Xalan xml.apache.org/xalan-j/index.html XT 4xt.org Oracle XML XDK technet.oracle.com/tech/xmli T Calling T Processor Server side java cp /u/csc309h/lib/saxon.jar com.icl.saxon.stylesheet xml_file xslt_stylesheet Client side PI embedded in XML <?xml-stylesheet type="text/xsl" href="file.xsl"?> Browser calls processor T Structure Stylesheet root element <xsl:stylesheet version="1.0"> or <xsl:transform version="1.0"> T Namespace refers to the year in which the URI was allocated by the W3C, not to the version of T Output element One or more templates 1

2 Defining templates <xsl:template match="" name="" mode="" > literal strings and result of expressions copied to result tree Templates Templates define how to output XML events A match attribute is used to associate the template with an XML element The value of the match attribute is a XPath expression <xsl:template match="xpathexpression"> A template is always instantiated with respect to a current node and a current node list. both are specified by the match Template Match Pattern Similar to XPath expressions, but allows top-level ' ' signs only 'child' and 'attribute' axes allowed allows '//' for descendants allows id(name) to start the expression SOURCE <CATALOG name = "CDs and Books"> <TITLE>The very best of</title> <ARTIST>Cat Stevens</ARTIST> <TITLE>Empire Burlesque</TITLE> <ARTIST>Bob Dylan</ARTIST> <BOOK> <TITLE>Prog. the WWW</TITLE> <AUTHOR>Sebesta</AUTHOR> </CATALOG> <xsl:apply-templates select="*"/> <xsl:template match ="CD"> <xsl:template match ="*"> Step Node List Matches 1 CATALOG I 1.1 CD CD BOOK I TITLE I TITLE I TITLE I AUTHOR I I I <xsl:apply-templates select="*"/> <xsl:template match ="CD"> <xsl:template match ="*"> Step Node List Matches 1 CATALOG 1.1 CD TITLE I CD TITLE I BOOK I TITLE I AUTHOR I TITLE I. I I <xsl:apply-templates select="*"/> <xsl:template match ="CD"> <xsl:template match ="*"> 2

3 Template Processing Model Process a list of source nodes to create a result tree fragment Concatenate result tree fragments for each node in the list Entire result tree is constructed by processing a list containing just the root node. Evaluation of a node usually results in a new node list Nodes in list follow document order Processing follows a depth-first order A node is processed by finding all the template rules with patterns that match that node, and choosing the best amongst them. The chosen rule's template is then instantiated with the node as the current node, and with the list of source nodes as the current node list. There is a default template if no matches found Correction CATALOG is not the root element / is the root element How come we get a match? Default templates Default Templates Invoking Templates root element attribute text comment PI namespace <xsl:template match="/ *"> <xsl:template match="@* text()"> <xsl:value-of select="." /> <xsl:template match="comment() processing-instruction()"/> can't be expressed in T. Built-in processor rule. <xsl:apply-templates select=""/> changes the current node and the current node list <xsl:call-template name=""> <xsl:with-param name="" select=""/> </xsl:call-template> does not change the current node or the current node list supports recursion Selection Selection <xsl:if test=""> </xsl:if> <xsl:choose> <xsl:when test=""> </xsl:when> <xsl:when test=""> </xsl:when> <xsl:otherwise> </xsl:otherwise> </xsl:choose> Title and artist for CDs and title and author for all books <xsl:template match ="CD BOOK"> Title <xsl:value-of select="'title' TITLE" /> <xsl:value-of select ="@name" /> <xsl:if test="name() = 'CD'"> Artist - <xsl:value-of select="artist" /> </xsl:if> <xsl:if test="name() = 'BOOK'"> <xsl:apply-templates select="cd Author - <xsl:value-of select="author" /> BOOK"/> </xsl:if> 3

4 Selection Title - The very best of Artist - Cat Stevens Title - Empire Burlesque Artist - Bob Dylan Title - Programming the WWW Author - Robert Sebesta Repetition <xsl:for-each select=""> Repetition Sorting CD titles <xsl:value-of select ="@name" /> <xsl:for-each select="cd"/> Title <xsl:value-of select="'title" /> Title - The very best of Title - Empire Burlesque By default nodes in the current list appear in document order Add one or more <xsl:sort> elements as children of <xsl:apply-templates> or <xsl:for-each> <xsl:sort select = string-expression (sort key) lang = nmtoken data-type = "text" "number" order = "ascending" "descending" case-order = "upper-first" "lowerfirst" /> Sorting Sorted CD titles <xsl:value-of select ="@name" /> <xsl:for-each select="cd"/> <xsl:sort select="title" /> Title <xsl:value-of select="'title" /> Title - Empire Burlesque Title - The very best of Sorting CD sorted by author, then by title <xsl:value-of select ="@name" /> <xsl:for-each select="cd"/> <xsl:sort select="artist" /> <xsl:sort select="title" /> Artist <xsl:value-of select="'artist" /> Title <xsl:value-of select="'title" /> Artist Bob Dylan Title Blood on the Track Artist Bob Dylan Title Empire Burlesque Artist Cat Stevens Title The very best of 4

5 Variables and Parameters <xsl:variable name="" select=""/> value of select is the value of the variable if no select, then value is the tree contained within the element <xsl:param name="" select=""/> value of select if the default value of the parameter, if no other value is specified on call top-level params can be set by the run-time environment can declare inside templates as well Variables <xsl:variable name="label"> </xsl:variable> <xsl:template match="/"> <xsl:text> Variable $label has been set to: </xsl:text> <xsl:value-of select="$label" /> Parameters <xsl:variable name="label"> </xsl:variable> <xsl:template match="/"> <xsl:text> Variable $label has been set to: </xsl:text> <xsl:value-of select="$label" /> saxon xmlfile xslfile title="programming the WWW" XML to XML Transformations Creating nodes <xsl:element name=""/> </xsl:element> <xsl:attribute name=""> </xsl:attribute> Coping nodes Current node (shallow copy) <xsl:copy /> Subtree (deep copy) <xsl:copy-of select=".." /> Numbering Numbering <xsl:number level = "single" "multiple" "any" count = pattern from = pattern value = number-expression format = { string } lang = { nmtoken } letter-value = { "alphabetic" "traditional" } grouping-separator = { char }grouping-size = { number } /> Can implement complex hierarchical numbering schemes <xsl:template match="*"> <xsl:number count="*" format="1.1 " level="multiple" /> <xsl:text> </xsl:text> <xsl:apply-templates select="*" /> 1 CATALOG 1.1 CD TITLE ARTIST COUNTRY COMPANY PRICE YEAR 1.2 CD TITLE ARTIST COUNTRY COMPANY PRICE YEAR 1.3 BOOK TITLE AUTHOR 5

6 Output Methods <xsl:output method="html xml text" /> XML <?xml version=1.0"?> <top> </top> <xsl:output method="text"/> <xsl:template match="/"> <xsl:apply-templates/> <xsl:template match="top"> <h1>the root node</h1> <xsl:value-of select="."/> Output Methods (saxon) xml (default) <?xml version="1.0" encoding="utf-8"?><h1>the root node</h1> html (default if first tag emitted) <h1>the root node</h1> text The root node Combining Stylesheets Include As if defined here <xsl:include href=uri-reference/> Import Importer has priority <xsl:import href=uri-reference/> 6